A multistage reactor including a vertical column is disclosed in U.S. Pat. No. 3,642,452 (Tarbourich). A bundle of vertical tubes serve the ascent and descent of liquid. Pipes arranged in coaxial relation with respect to said tubes carry gas and a down tube is provided for better mixing of the phases.
Many prior art patents have discussed many means to mix two phases. In U.S. Pat. No. 3,452,966 (Smolski) liquid such as water is mixed with air via an open-ended vertical tube. The lower end of the tube is submerged in the liquid above a gas bubble generator. A helical baffle is provided to create a turbulence in the tube and assist in adsorption of the gas into the liquid.
In U.S. Pat. No. 3,738,353 (Santoleri) a series of sparger tubes are mounted below a heat exchanger within the confines of a baffle plate. Air bubbles are discharged upward which increases the transfer of heat from a waste-water stream. In U.S. Pat. No. 4,440,698 (Bloomer), a heat exchanger is provided whereby jets are created in the duct through which the gas flows which contacts the exchanger. Liquid is sprayed over the heat exchanger and high velocity jets of gas pick up liquid and carry it into the exchanger.
Finally, U.S. Pat. No. 5,376,311 (DeGuzman) discloses an apparatus for the aeration of liquids by passage of a gas through a porous diffuser thereby producing microsized bubbles dispersed in the liquid. A porous tubular member is provided in approximately the center of the apparatus.